1988 Louis Roederer Cristal Brut--is it still ok?

[skylarque]

My husband's publisher gave him a 750ml bottle of 1988 Louis Roederer Cristal Brut in 1996, to celebrate his book opening on the bestseller list. We would like to know two things: (1) the value of the wine if we were to sell it, and (2) whether the wine would still be good, given the conditions under which it has been stored. Obviously, we would not want to either gift it or sell it if there is a chance it is not good. Since we received it, it has been stored on its side (although I just read here that doesn't matter), in our enclosed kitchen pantry. The pantry is a dark closet, and would be about the temperature of the house or cooler (never more than 78 degrees -- but I don't know if that's too high). What do the experts say? (The labels are mint, as it has been in a see-through gold wrap all these years.)